Pilot burner constructions and the like



y 18, 1965 L. F. CRAEMER 3,184,337

PILOT BURNER CONSTRUCTIONS AND THE LIKE Filed Jan. 3. 1962 FIG.2

LAMBERT F. CRAEMER INVENTOR HIS ATTORNEYS United States Patent 3,184,337 PILOT BURNER CONSTRUCTIONS AND THE LIKE Lambert F. Craemer, Santa Ana, Califl, assignor to Robertshaw Controls Company, Richmond, Va., a corporation of Delaware Filed Jan. 3, 1962, Ser. No. 164,032 3 Claims. (Cl. 136-4) This invention relates to pilot burners of the primary aerated type for maintaining an ignition flame for a main burner and for heating the hot junction of the thermocouple of a fuel control system.

A problem frequently encountered in pilot burners is that of lint collecting at the primary air opening of the burner to the extent that an insufficient amount of air is mixed with the fuel which causes the pilot flame to be extinguished.

Another problem frequently encountered is the extinguishment of the pilot flame caused by drafts. If rapidly moving air enters the fuel passage at the primary air inlet and proceeds up the passageway to the outlet of the burner, the flame may be blown away from the outlet. This is the result when the rate of flow through the passageway greatly exceeds the rate of propagation of the flame. Conversely, if rapidly moving air enters the fuel passageway from the burner outlet in opposition to the fuel flow, the pilot flame may be forced back down the fuel passageway and be extinguished for lack of suflicient oxygen. This is the result of the rate of flame propagation exceeding the rate of fuel flow out of the burner.

It is therefore an object of this invention to reduce the collection of lint at the primary air inlet of a pilot burner.

It is a further object of this invention to prevent the extinguishmcnt of the pilot flame of a burner caused by drafts.

Another object of this invention is to reduce the effects of drafts or wind variations on the pilot flame of a burner.

These and other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a side elevational view of one form of the invention with parts cut away for clarity.

FIGURE 2 is an end view of the burner of FIGURE 1 with the thermocouple removed for purposes of clarity.

FIGURE 3 is a side elevation of another form of pilot burner with portions cut away for purposes of clarity.

FIGURE 4 is an end view of the pilot burner of FIG- URE 3 with the thermocouple removed for purposes of clarity.

Referring to the form of invention illustrated in FIG- URES l and 2, a pilot burner is illustrated comprising a. body which is formed from a pair of complementary sheet metal members 12 and 14. Depressions are formed in members 12 and 14 for providing a fuel conduit or passageway 16. One end of passage 16 provides an inlet opening 18, and the other outlet or burner port 20.

Body portion 10 is cut away at 22 adjacent inlet opening 18, and formed in body 10 by depressions in members 12 and 14 is a cylindrical recess 24 adjacent cut away portion 22. Mounted in recess 24 is a threaded connecting element 26 for connecting the pilot burner with a source of fluid fuel. Orifice 28 of connecting element 26 projects into inlet 18 and provides a fuel injection for fuel passage 16. The walls of passage 16 adjacent inlet opening 18 are laterally spaced from orifice 28 providing a primary air inlet for the burner.

The walls of a portion 30 of passage 16 converge from inlet opening 18 to form a Venturi throat 32 of reduced diameter downstream from inlet 18. Passage 16 has a straight portion 34 beyond Venturi throat 32, which connects with a curved portion 36. The wall of passage 16 diverges from Venturi throat 32 to the relatively large ree burner port or outlet 20 at the end of curved portion 36.

Formed on the side of body 10 adjacent the outlet 20 is a support bracket portion 38. Complementary depressions in members 12 and 14 form a cylindrical recess 40 for receiving a thermocouple 42. A pair of vertically spaced slots 44 are formed in recess 40 for receiving shoulders 46 of thermocouple 32. Thus, it is seen that the flame emitting from burner port 20, will impinge on the thermoelectric junction 48 of thermocouple 42 which may be connected by means of lead 50 in circuit with an electromagnet of a fuel control device of a main burner (not shown).

With the above described construction, the relatively large primary air inlet permits passage of large lint particles. These particles are entrained in the rapidly moving fuel-air stream through passage 16 and are carried out the large burner port 20 into the flame where they are incinerated.

Referring now to the modified form of FIGURES 3 and 4, wherein like structure is identified by corresponding reference numerals, fuel passage 16 has a curved portion 154 which connects straight portion 34 with a burner port or outlet 156. Outlet 156 is so disposed that the flame will impinge downwardly on the thermoelectric junction 48 of thermocouple 42. Curved portion 154 delines a degree bend in passage 16. Thus, the direction of flow through passage 16 is reversed between the inlet and the outlet, and the burner port or outlet 156 defines a plane which is parallel to the plane defined by inlet 18. Since the primary air inlet and the burner outlet are oriented in substantially the same direction, any draft directed toward the primary air inlet tending to blow the pilot flame away from the burner, would be counteracted by a corresponding increase in pressure at the burner port tending to force the pilot flame back down the fuel passage. The net effect would be that the flame would remain positioned at the outlet of the burner as desired.

While specific forms of the invention have been dis closed, it will be understood that various modifications of structure may be effected without departing from the scope of this invention as defined by the following claims.

I claim:

1. A pilot burner comprising in combination, a pair of generally flat sheet metal members secured together to form a body portion, each of said sheet metal members having complementary depressions formed therein to produce a conduit for a fluid fuel formed in said body portion and having a primary air opening whose inlet edges lie in a plane and a fluid fuel outlet port parallel to said plane and defined by spaced edges of said sheet metal members and defining a parallel plane with the plane de fined by said air inlet, the wall of said conduit converging from said inlet to form a Venturi throat downstream of said inlet and diverging from said Venturi throat to said outlet and curving adjacent said outlet, each of said sheet metal members having cutaway portions to form said air inlet, said sheet metal members having complementary depressions adjacent and upstream from said cutaway portions to form a fuel injection means supporting recess, and fuel injection means mounted on said body portion in said recess and projecting into said inlet, the walls of said sheet metal members adjacent to and downstream of said inlet being laterally spaced from said fuel injection means, said inlet edges being formed by said walls upstream from said fuel injection means and at the beginning of said converging portion of said conduit, whereby lint entering said primary air inlet will be entrained in the rapidly flowing fluid through said conduit to be incinerated at said burner port, said combination further comprising a laterally projecting support bracket on said body portion formed by extensions of said sheet metal members having complementary depressions to form a cylindrical recess in said support bracket, a thermocouple mounted in said cylindrical recess, and having a thermoelectric junction disposed adjacent said burner port, whereby the flame caused by combustion of fuel at said burner port will impinge on said thermoelectric junction.

2. A pilot burner comprising in combination, a pair of generally flat sheet metal members secured together to form a body portion, each of said sheet metal members having complementary depressions formed therein to produce a conduit for a fluid fuel formed in said body portion and having a primary air opening whose inlet edges lie in a plane and a fluid fuel outlet port parallel to said plane and defined by spaced edges of said sheet metal members and defining a parallel plane with the plane defined by said air inlet, the wall of said conduit converging from said inlet to form a Venturi throat downstream of said inlet and diverging from said Venturi throat to said outlet and curving adjacent said outlet, each of said sheet metal members having cutaway portions to form said air inlet, said sheet metal members having complementary depressions adjacent and upstream from said cutaway portions to form a fuel injection means supporting recess, and fuel injection means mounted on said body portion in said recess and projecting into said inlet, the walls of said sheet metal members adjacent to and downstream of said inlet being laterally spaced from said fuel injection means, said inlet edges being formed by said walls upstream from said fuel injection means and at the beginning of said converging portion of said conduit, Whereby lint entering said primary air inlet will be entrained in the rapidly flowing fluid through said conduit to be incinerated at said burner port, said combination further comprising a laterally projecting support bracket on said body portion formed by extensions of said sheet metal members having complementary depressions to form a cylindrical recess in said support bracket, a thermocouple mounted in said cylindrical recess, and having a thermoelectric junction disposed adjacent said burner port, whereby the flame caused by combustion of fuel at said burner port will impinge on said thermoelectric junction, in which combination said cylindrical last named recess and said thermocouple are parallel to the axis of said fuel injection means supporting recess, and said wall of said conduit curves 180 to direct the flame discharged at said fuel outlet in alignment to said thermoelectric junction.

3. In combination, a pair of complementary generally flat sheet metal members secured together and formed to produce complementary depresssions which when joined together along a juncture plane form a generally flat pilot burner body, said complementary depressions forming a conduit for fluid fuel formed in said body having a primary air opening whose inlet edges lie in a plane and an outlet opening terminating in a plane parallel to said inlet edges, said complementary depressions having complementary curved portions to form said conduit with a curved portion terminating at said outlet, the wall of said conduit converging from said air inlet to form a Venturi throat of reduced diameter upstream from said air inlet and diverging from said Venturi throat to said outlet, said sheet metal members having complementary semicylindrical depressions forming a fuel injector supporting cylindrical conduit upstream from said air inlet, a cylindrical fuel injector mounted in said cylindrical conduit and projecting into said inlet, said sheet metal members being cut at said air inlet and being laterally spaced from said fuel injector thereby defining said primary air inlet disposed upstream from said fuel injector and at the beginning of said converging portion of said conduit, whereby flow through said conduit will entrain lint entering said primary air inlet to said outlet to be incinerated by combustion of said fuel at said outlet, said sheet metal members projecting laterally from said fuel injector supporting cylindrical conduit to form a laterally projecting support bracket having complementary depressions forming a thermocouple supporting recess in said bracket, a thermocouple mounted in said thermocouple supporting recess, said thermocouple having a thermoelectric junction disposed adjacent said fuel outlet, whereby the flame caused by combustion of fuel at said fuel outlet heats said thermoelectric junction.

References Cited by the Examiner UNITED STATES PATENTS 968,176 8/10 Mellinkoff 158116 2,303,183 11/42 Wasson 136-413 2,665,321 1/54 Flagg.

FOREIGN PATENTS 24,030 11/21 France. 10,364 1903 Great Britain.

210,301 1/24 Great Britain.

JAMES W. WESTHAVER, Primary Examiner.

FREDERICK L. MATTESON, 111., Examiner. 

1. A PILOT BURNER COMPRISING IN COMBINATION, A PAIR OF GENERALLY FLAT SHEET METAL MEMBERS SECURED TOGETHER TO FORM A BODY PORTION, EACH OF SAID SHEET METAL MEMBERS HAVING COMPLEMENTARY DEPRESSIONS FORMED THEREIN TO PRODUCE A CONDUIT FOR A FLUID FUEL FORMED IN SAID BODY PORTION AND HAVING A PRIMARY AIR OPENING WHOSE INLET EDGES LIE IN A PLANE AND A FLUID FUEL OUTLET PORT PARALLEL TO SAID PLANE AND DEFINED BY SPACED EDGES OF SAID SHEET METAL MEMBERS AND DEFINING A PARALLEL PLANE WIT THE PLANE DEFINED BY SAID AIR INLET, THE WALL OF SAID CONDUIT CONVERGING FROM SAID INLET AND DIVERGING FROM SAID VENTURI THROAT TO SAID OUTLET AND CURVING ADJACENT SAID OUTLET, EACH OF SAID SHEET METAL MEMBERS HAVING CUTAWAY PROTIONS TO FORM SAID AIR INLET, SAID SHEET METAL MEMBERS HAVING COMPLEMENTARY DEPRESSIONS ADJACENT AND UPSTREAM FROM SAID CUTAWAY PORTIONS TO FORM A FUEL INJECTION MEANS SUPPORTING RECESS, AND FUEL INJECTION MEANS MOUNTED ON SAID BODY PORTION IN SAID RECESS AND PROJECTING INTO SAID INLET, THE WALLS OF SAID SHEET METAL MEMBERS ADJACENT TO AND DOWNSTREAM OF SAID INLET BEING LATERALLY SPACED FROM SAID FUEL INJECTION MEANS, SAID INLET EDGES BEING FORMED BY SAID WALLS UPSTREAM FROM SAID FUEL INJECTION MEANS AND AT THE BEGINNING OF SAID CONVERGING PORTION OF SAID CONDUIT, WHEREBY LINT ENTERING SAID PRIMARY AIR INLET WILL BE ENTRAINED IN THE RAPIDLY FLOWING FLUID THROUGH SAID CON DUIT TO BE INCINERATED AT SAID BURNER PORT, SAID COMBINATION FURTHER COMPRISING A LATERALLY PROJECTING SUPPORT BRACKET ON SAID BODY PORTION FORMED BY EXTENSIONS OF SAID SHEET METAL MEMBERS HAVING COMPLEMENTARY DEPRESSIONS TO FORM A CYLINDRICAL RECESS IN SAID SUPPORT BRACKET, A THERMOCOUPLE MOUNTED IN SAID CYLINDRICAL RECESS, AND HAVING A THERMOELECTRIC JUNCTION DISPOSED ADJACENT SAID BURNER PORT, WHEREBY THE FLAME CAUSED BY COMBUSTION OF FUEL AT SAID BURNER PORT WILL IMPINGE ON SAID THERMOELECTRIC JUNCTION. 